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Brain Electrical Oscillations Signature ProfilBrain Electrical Oscillations Signature ProfilBrain Electrical Oscillations Signature ProfilBrain Electrical Oscillations Signature Profile e e e of Experiential Knowledgeof Experiential Knowledgeof Experiential Knowledgeof Experiential Knowledge

Champadi R. Mukundan*, Nilesh B. Wagh, Gunjan Khera, Shraddha U. Khandwala,

Tara L. Asawa, Namrata M. Khopkar, Dharmistha D. Parekh

Forensic Psychology, Directorate of Forensic Sciences, Gandhinagar, Gujarat, India

Number of Text Pages (with Figures & Tables) : 37

Number of Figures : 3

Number of Table(s) : 5

* Corresponding author:

Prof. C.R. Mukundan, Ph.D. (Former Professor & Head of Clinical Psychology) Research Consultant to TIFAC-DFS Project on “Normative Data for Brain Electrical Activation Profiling” 40-27 Soham, 6th Cross Christ School Road Bangalore, India. Phone: +91-9845177355 Fax: +91-8041508919 Email: crmukundan@gmail.com

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ABSTRACTABSTRACTABSTRACTABSTRACT

In memory systems, ‘remembering’ is more attributed to ‘experiential knowledge’ (EK),

while ‘knowing’ is related to mere recognition. Brain signature(s) specific to

remembering as distinct from knowing will have enormous applied value including its

forensic use. The present study aims to determine the validity of a newly developed

technique, Brain Electrical Oscillations Signature (BEOS), in differentiating the

individuals with specific EK from those without. Sample consisted of an experimental

group with 56 normal volunteers who participated in specific activities and a control

group of 54 matched individuals who had only the knowledge of these activities without

actual participation. EEG was recorded while each participant had a series of auditory

presentations of short verbal statements related to the previous ‘activity session’.

Results showed that the experimental group had significantly more EK scores than the

control group. Receiver Operating Characteristics (ROC) curve revealed high sensitivity

and specificity for the BEOS profiling system.

Key Words: Key Words: Key Words: Key Words: Forensic science, Brain Electrical Oscillations Signature (BEOS), Neuro

Signature System (NSS), probe, Experiential Knowledge (EK), remembrance, knowing,

Receiver Operating Characteristics (ROC) curve, sensitivity, specificity.

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IntroductionIntroductionIntroductionIntroduction

Information is retrieved from memory during recognition as well as remembrance

of past personal episodes. Recognition of familiarity requires retrieval of information

acquired in the past, which form a major spectrum of neural activities related to

perception. Retrieval of past personal events, often called remembrance of

autobiographical episodes, may take place intentionally and when cued by stimuli. In

perception, the retrieved information facilitates recognition of entities of the external

world (1), whereas in remembrance, the individual becomes aware of the retrieved

information. All learning contributes to the knowledge bank, and retrieval from this

source facilitates not only recognition of entities but also understanding of different

aspects of relationship among entities across temporal and spatial dimensions. Mandler

(2) differentiated between ‘knowing’ and ‘remembrance’ as two memory systems; and

Tulving (3,4) further substantiated multiple memory systems. Functional neuroimaging

studies have shown that brain activation during remembrance of autobiographical

episodes is distinctly different from that seen in ‘knowing’. Studies report extensive

ventral brain activation, including that of anterior cingulate cortex, orbitofrontal cortex,

and medial temporal cortex during remembrance; while ‘knowing’ correlated mainly with

smaller activation patterns in dorsofrontal prefrontal cortex (5-15). These studies have

shown that ‘knowing’, especially that leading to recognition may engage minimal brain

resources in comparison with remembrance of personal past events, which may have

temporal and spatial references, sensory and motor mental imageries, and emotional

experiences, which require extensive neural participation. Source memory provides the

contextual, temporal, and spatial references required to correctly identify or locate the

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autobiographical episode for retrieval. Source memory has a different neural localization

compared to the main autobiographical episode, as shown in various neuroimaging

studies (16-28). Remembrance of an experience is almost like reliving the same

experience when all its original components are recalled (29). Remembrance may

therefore include recreation of sensory mental imageries (30-36), and motor mental

imageries (37-43). As seen in these studies transcoded verbal details of the episode

may be used for the recreation of the original mental imageries.

Moscovitch (44-47) described two types of retrieval processes. One is associative

and dependent on cues whereas the other is strategic. Cue dependent retrieval is

automatic and mandatory. Mostly external stimuli may serve as cues; the cue could be

provided by a specific characteristic or meaning of a stimulus, which makes the person

remember the past episode. Moscovitch described the cued retrieval both automatic and

mandatory. Physical characteristics or semantically interpreted meaning may be

considered to serves as cue for triggering the recall of the related information. The

cueing effect is considered present only in one who is able to link the stimulus

characteristic with a specific past experience or knowledge. The association of the

cueing stimulus with the stored information may be logical or purely incidental. When

there is no logical association present, a stimulus may serve as a cue for the recall of

the specific information only in one in whom that specific association exists. A verbal

statement referring to the episode often serves as the most efficient cue for one to

retrieve the past event and become aware of it. Remembrance of experience is possible

only for one who has had it and one can remember only an experience that one has had

or believed to a have had. A cue or reference does not lead to the remembrance of an

experience or participation in it if one did not take part or have the said experience.

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Experiencing emotions during remembrance of personal episodes is well known

in the day-to-day life for everyone. Retrieved emotions may almost equal the same

original experience. Its intensity and duration may vary based on the personal

significance of the original experience. Significant differences in the intensity, vividness,

and components may exist from one remembrance to another in the same individual.

Quality of remembrance of a shared experience or event witnessed may differ from

individual to individual. The triggering of the remembrance may not be uniformly time

locked to the cueing stimulus across stimuli, occasions, and individuals. There are

frequent instances when one remembers a name or details of a personal event much

later after receiving a triggering cue. None of these factors can be differentially known or

predicted presently from outside by a measuring system. Remembrance is indeed a

complex neurocognitive process unlike other cognitive processes such as arousal of

attention, attentional allocation, recognition, and anticipation. Neuroimaging can indicate

the brain areas activated during remembrance but it cannot be considered to reflect the

subjective quality of remembrance. Similarly, a surface EEG recording is only a

reflection of widespread neural activity within the brain and the changes that accompany

processing related to cognitive and motor events. Remembrance of autobiographical

episodes may be considered one of the complex cognitive states, as complex as

experiencing itself, requiring extensive neural participation.

Brain electrophysiology studies have firmly established the role of electrical

oscillations of the brain in cognitive states. Electrical oscillations of the neurons in

multiple frequencies contribute to extensive electrical changes in the brain and

Electroencephalograph (EEG) recorded from the scalp is a reflection of such changes

generated from within. Oscillating neuronal networks producing synchronous activity

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represent the dynamic functional bridge between consciousness, cognitive processes,

behavior, and neurons (48). In diseases affecting the brain and its functions, the

electrical oscillations show significant changes and recording these abnormalities are

now integral part of disease diagnosis and monitoring. Wealth of studies have shown

the relationship between electrical oscillations and cognitive states representing

perception, memory, and thinking (49-62). These studies have shown that generation of

gamma, beta, alpha, theta, and delta frequencies are closely associated with different

cognitive processing states. These studies have reported patterns in EEG frequency,

power, and event related potentials in various cognitive processing conditions. There

have been relatively fewer electrophysiological studies, which differentiated

‘remembrance’ from ‘knowing’. Freidman & Johnson (63) in their review of ERP and

functional neuroimaging studies compared the results from the two modes of

investigation in explicit memory and found good correspondence between the results of

the two types of studies. Recognition memory tested using ERP occurring around 300

ms after the stimulus onset could differentiate between old and new stimuli (63,64). ERP

study by Curran et al. (65) using recognition of familiarity in words presented earlier in

the study along with new words demonstrated the adverse effect of Medozolam, a

pharmacological agent with specific effect to produce amnesia on recall of remembered

words as shown by P300 and FN400 potentials. Remembrance of words alone was

affected adversely in the drug condition of amnesia, whereas the condition did not affect

recognition of familiarity of the words. The FN400 peaking at 400 ms in the midfrontal

area is found to have different functional significance compared to the same peaking at

600 ms in the parietal area (66-72). Duzel et al. (61) compared remembrance and

knowing using event related potentials during recognition of a list of words in normal

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subjects. Some of the words in the list referred to narratives of events presented in a

prior session. They considered the earlier narrative to elicit “autonoetic” awareness by

presenting event related words as against “noetic” awareness produced by new event

unrelated words in the list. The ERP showed a distinct positivity in the 600 – 1000 ms

range when narrative related words were presented indicating remembrance of the

narrative, seen bilaterally predominantly in the frontal areas and lesser in the parietal

areas, which was absent in the other conditions tested. They could differentiate between

false and true remembrance, whereas mere false and true recognitions did not show

such differentiation in the ERPs. In their subsequent study Duzel et al. (73), using both

the PET and the ERP, the neural profiles of information recall related to past episodic

tasks was compared with the recalls in semantic tasks. Episodic retrieval was found to

be associated with activation in the right prefrontal cortex and posterior cingulate cortex

in the PET and sustained frontopolar positivity in the ERP recordings. Semantic recall

was found to be associated with the typical left frontal and temporal activation seen in

other studies. The late positivity seen (61) in the time domain analyses of remembrance

data represented an increase in the slow oscillations in the EEG. Attending to or being

aware of internal cognitive processing as in remembering needs one to look away from

the external world/stimuli, thereby blocking its perception transiently so that attention

can be directed inward to the internal processing. Such inward attention may also be

required for the recreation of mental imageries and thoughts and for selectively

attending to them for further processing. Harmony et al. (62) and Fernandez et al. (57)

elicited evidence for such specific association of delta band frequencies with awareness

of internal processing. Robinson (60) in his study indicated that 4 Hz activity is related to

behavioral arousal, which is negatively related to 10 Hz activity. The importance of

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frequency bands in the theta and alpha ranges have been demonstrated in several

studies. Klimesch et al. (58) suggested that synchronization of theta and alpha

frequencies across distant neural areas is for specific processing of internal mental

contexts during cognitive processing. Klimesch et al. (59) indicated that theta

oscillations represent hippocampal engagement required for retrieving from long term

cell assemblies in episodic memory recalls. The role of gamma activity in the 35 – 85 Hz

range during retrieval of information, especially visual mental imageries has been

demonstrated in several studies (49-51,53,55,56,74,75). The frontal participation is

associated with the use and recall of the verbally transcoded information using which

the visual the mental imagery can be reconstituted, which is accomplished in the

posterior areas.

The purpose of the present study was to determine the sensitivity-specificity and

other related characteristics of the technique called Brain Electrical Oscillations

Signature (BEOS) profiling developed by Mukundan CR (Patent application pending) for

identifying individuals with specific autobiographical episodes or experience. Specially

designed verbal statements presented as probes in auditory mode referred to the

participation of the individual in an activity specially designed for the test. The test

recorded the electrical activity from the scalp of a subject using multiple electrodes and

computed the changes in the activity while listening to the list of probes. The probes

were expected to provoke or trigger the remembrance of the experience only in those

who participated in the referred activities. If knowledge of the experience was present,

the BEOS profiling extracted the accompanying remembrance specific changes in the

electrical oscillations. “Signature” refers to a set of specific changes defined as markers

of the process of remembrance. The changes are not expected to be time locked as in

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other ERP paradigms, as remembrance and the accompanying changes may occur at

varying latencies.

The word ‘provoked’ or ‘triggered’ is preferred to ‘induced’ for referring to the

neural activity and the electrical changes accompanying remembrance using the

present probe presentation method, as the changes will not be induced in all subjects.

The probe would serve as a cue only if it provides a contextual reference and triggers

the retrieval of a linked past event. Further, this can happen only if the event itself has a

personal significance to the subject and therefore has the chance to be retrieved. A cue

may not work if the original experience does not have any personal significance and if

one does not remember it. The triggering effect of a probe may be incidental and not

logical as it makes meaning only to the person who has had the experience and finds an

association between the cue and components of the experience. Probes are statements

referring to the alleged involvement and direct participation in an activity by a subject.

The system presented a recorded version of sequentially arranged probes at fixed

intervals. Several probes arranged sequentially as ‘Scenarios’ directly refer to the

different components/phases of the event. The sequentially presented probes form a

‘stream of thought’ (76-79) in the listener, in which the central idea moves from one to

another in sequence, with reference to the context whenever possible. Words are

selected carefully for maintaining the core theme and the contextual reference intact

though out, in which verbal awareness of experiences (80,81) is used to trigger

remembrance of the original experience. The subject is instructed to remain with eyes

closed and without movement, and need only listen to the probes without giving any

response. The subject is also given opportunity to either read through or listen to the list

of the probes before they are presented during the BEOS recording. This eliminates

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novelty effects and other possible emotional responses related to listening to the probes

for the first time. BEOS profiling records the electrical activity associated with the

presentation of a probe from multiple channels and compares the changes in each

channel with the preprobe baseline, and identifies specific predefined patterns in the

changes. The probes are presented one after the other and continuous EEG with probe

details is acquired. The study aimed at identifying individuals who had a specific

experience by differentiating them from those who had only knowledge of the activities.

The comparison of the responses of the two groups in the analyzed results of the BEOS

profiles, using the same set of probes, signal processing, and analysis of the results

helps in the computation of sensitivity, specificity, and related factors.

MethodsMethodsMethodsMethods

Participants

The study consisted of comparison of the brain electrical activities of subjects in

an experimental group with that of a control group, recorded while each subject listened

to a list of probes referring to activities, which the subjects in the experimental group had

carried out whereas the control group subjects had only knowledge. The research staff

identified volunteers from normal population who lived in the same city within a radius of

about 5 kilometers. Those who volunteered for the study were invited for a selection

process in the laboratory. Subjects were selected from ages 15 to 70 yrs and both male

and female volunteers were included in the study. Informed consent was obtained from

all participants, and ethical aspects of the project were monitored by the research

monitoring committee. The experimental procedure of this study was in accordance with

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the recent version of the Ethical guidelines for Biomedical Research on Human

Participants as mandated by the Indian Council for Medical Research (ICMR) (82).

Materials and Design

To begin with, each was administered the General Health Questionnaire (83) for

a quick screening for the absence of psychiatric morbidity. This was done by the Indian

standardized version of GHQ-12 (84). The selected subject was randomly assigned to

the experimental or control group. Immediately after obtaining a written informed

consent for the study, each subject was tested by s small battery of psychological tests.

Intelligence was assessed using J.C. Raven’s Standard Progressive Matrices and

learning, and memory functions using the Learning & Memory Functions subscale from

the NIMHANS Neuropsychological Tests battery (85). The percentile scores on the

progressive matrices test was taken to indicate fluid intelligence based on complex

abstract reasoning. The Learning & Memory Functions test has a verbal and visual form.

In the verbal form, a passage is read out to the subject, which the subject must recall

immediately. The same passage is read again in a second and third trial, with immediate

recalls in both the trials for assessing the learning function. In a fourth trial, which

followed the third trial, the subject is instructed to recall the same passage from memory

after an interval of 10 minutes. The visual form consisted of a complex figure, which was

administered in the same manner as the verbal test. The number of units of information

recalled formed the sores for each trial in the verbal and visual forms. Of the 120

subjects who were initially identified and selected for the study, 110 completed the

BEOS profiling. The experimental group consisted of 56 volunteers and the control

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group had 54 subjects. Table 1 gives the means and SDs of the age and scores of

various tests administered.

Procedure

After the completion of the psychological tests, each subject in the experimental

group was assigned a specially designed task consisting of activities to be carried out in

a designated room, as per an instruction booklet. A video recording of the activities of

the experimental subjects in the ‘activity room’ was not carried out as several subjects

refused video recording of their movements in the room while obtaining the informed

consent. According to the instructions, ‘the subject retrieved a key for the test room,

opened the ‘activity room’, switched on the lights in the dark room, and inspected the

contents in the room’. As per the instructions, the subject ‘searched and retrieved an

iron rod from a locked cupboard, used it to break a large clay piggy back, which needed

to be hit hard for breaking, and then collected large number of coins and some

chocolates that dropped out of the pot. The coins were collected in a plastic bag and the

broken parts of the piggy bank in another plastic bag. The room was cleaned by using a

broom kept in the room, and the plastic bag containing the broken pieces of the piggy

bank was disposed off in a wastepaper basket in the corner of the room. The subject

switched off the lights, locked the room, and left the room with the coins and the

chocolates.’ A research staff later examined the ‘activity room’ looking for evidence of

breakage of the piggy bank and for ascertaining that the coins were removed. The

subjects in the control group were given the instruction booklet and requested to study

the contents. Subjects in both the groups were administered BEOS profiling using list of

probes referring to the activities carried out by the experimental group subject in the

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‘activity room’. The BEOS profiling was done 2-3 weeks after the subject took part in the

above activity.

Probes

The probes referred to the different components of the activity carried out by the

subjects, in the sequence in which the activities were deemed to have taken place. The

probes that directly refer to the test room activities are called the Target probes.

Additionally there were two sets of probes called the neutral probes as they measured

the baseline changes due to semantic interpretation and also the effects of impersonal

mental imageries. Two more sets of probes may be used when the test is used for

forensic purposes. One set called the control probes are probes referring to significant

events in the personal life of the subject. The positive findings on the control probes

serve for self-validation of the technique as they refer to events that indeed took place.

The fourth set called the Target-B probes may refer to an alternate version(s) of events,

which are opposed to subject’s involvement as stipulated in the Target A set of probes.

In the present investigation, there were no control probes, as they required in-depth

interview and independent verification of the information provided by each subject about

the personal past. There was no scope for the Target-B probes in the present study. The

activities carried out in the ‘activity room’ by a subject form the basis for the Target–A

probes. A ‘scenario’ consisted of a set robes referring to one set or phase of activity, as

envisaged by the examiner. Each probe was assigned a code according to the

guidelines provided in the NSS manual. A code is assigned based on what the examiner

expects the probe to provoke in a subject who listens to it. For example, a set of codes

would direct the program to look for pattern indicating presence of sensory mental

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imagery, whereas another set of codes directs the program to look for patterns

indicating presence of motor mental imagery. A third set of codes directed the program

not to look for changes defined related to either type of mental imageries. Use of the

codes increases the specificity of changes looked for in the analysis, as the program

decides on the presence of ‘experiential knowledge’ only when it identifies the pattern

associated with the respective code.

The length of each probe varies in terms of the number of words, the language

used, and the speed of articulation used for its oral presentation. The purpose of a probe

is to serve as cue for the retrieval of an associated memory, if present, and not for its

mere semantic interpretation. The probes are presented in the language most

comfortable to a subject. An audio presentation in different languages may last for

different durations. The duration of a probe is kept within a maximum duration of 3.5 sec

and the shortest statement may have two words. Though the speed of recording of

words can be varied minimally depending on subject’s preferences, a constant speed

was used for al subjects who were presented with probes in one language. Each probe

is presented in first person as “I read the instructions”, “I walked to the test room”, “I

opened the lock,” etc. The probe is read out for recording without any emotional effects.

Male or female voices are used for recording depending on the gender of the subject to

be tested. Probes were presented in Gujarati, Hindi, or English, as the subjects of the

study preferred one of these languages.

The probes were typed into the computer in English. If the probes were presented

in any other language to a subject, the articulated speech sounds were converted into

English and entered. The Visual and Auditory Stimulus Program (VASP) of the Neuro

Signature System (NSS) used for BEOS profiling recorded them into the computer for

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audio presentation. The VASP marks each probe with the necessary event markers and

allows adjustment of the interval between consecutive probes. The probes were

arranged in nine scenarios. The first two scenarios consisted of list of neutral probes (4

and 6 probes). The next six scenarios contained list of probes related to sequence of

activities in the ‘activity room’. They were Scenario 3 (12 probes) related to visiting the

laboratory and being given the instruction booklet, Scenario 4 (7 probes) related to

entering the locked room, Scenario 5 (13 probes) of observing the objects in the ‘activity

room’, Scenario 6 (12 probes) related to deciding the action strategy, Scenario 7 (8

probes) related to breaking the piggy bank and collecting the coins, and Scenario 8 (16

probes) related to cleaning up and leaving the room. A ninth scenario had probes (13

probes) related to the visit to the laboratory, undertaking psychological tests, and some

irrelevant probes related to watching cricket on video. Each subject read the list of

probes before the test.

The examiner informed each before starting the BEOS profiling that they have to

recall the probes after completing the recording. After recording the EEG with the eyes

open and closed conditions for 3 minutes each, and before starting the presentation of

the probes, a frame by frame video display of the objects in the ‘activity room’ was made

to the subject on a computer screen. They were informed that the video display was of

the objects in the ‘activity room’ and they were merely to watch the display without

making any response. This gave the subjects of the experimental group opportunity to

recognize the objects and remember what they did in the ‘activity room’, whereas there

was no question of such recognition for the subjects in the control group, though they

readily recognized them as otherwise familiar objects. They also knew that the display

was of objects in the ‘activity room’ about which they had read about in the instruction

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booklet. The video display can prime the memory of the objects and activities in the

‘activity room’ in the experimental subjects. It may even prime such memories in the

control subjects if they had any prior significant experience relating them. In the absence

of any such event, the display could only lead to new perceptions of familiar objects

about which some information was already provided in the instruction booklet. The

probes were presented to the subject at 80 dB level, through a sound system placed a

meter away from the subject. The subjects sat through with the eyes closed and listened

to them while continuous acquiring of the EEG. All subjects went through a post-test

interview. Last 22 subjects of the control group completed a post-test rating of the

familiarity of the probes in terms of their reference to the objects and events in their

personal life. They rated each probe on total strangeness, minimal, moderate, and

maximum levels of personal reference.

EEG recording

The command for presentation of a probe is sent by the NSS while monitoring the

online EEG of the suspect. Thirty channels of NSS acquire the EEG using a custom-

made Electrocap with linked earlobe electrodes as reference. The EEG was recorded

from Fp1, AF3, F7, F3, FT7, FC3, T3, C3, TP7, T5, CP3, P3, O1, Fp2, AF4, F8, F4, FT8,

FC4, T4, C4, TP8, T6, CP4, P4, O2, Fz, FCz, Cz, CPz electrode sites. Additional two

channels were used for recording vertical and horizontal eye movements. The

bandwidth used for EEG acquisition was 0.16 – 100 Hz without any other hardware

filtering. The online EEG was analyzed for energy spectrum and the values were used

for online control of probe presentation. These values were displayed as brain maps.

The NSS uses a program by which a probe is presented only if the power values in

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different frequency ranges are within preset ranges as derived from the EEG of the eyes

closed condition of the subject. If the value in any frequency range is outside the preset

percentage range, the probe presentation is delayed until the value returns to the

optimum range. Continuous delay warns the examiner of the event and the consequent

stoppage of probe presentation. The continuous video of the subject recorded from the

front of the subject, and the audio presentation of the probes as heard by the subject

and the orthographic form of the probe were recorded in the NSS along with the EEG,

all of which were time locked to each other and encrypted to form a single file. The

output data file cannot be opened for any alteration of its components and the raw data

file alone is always automatically selected for analysis. At the end of the recording after

presentation of all the probes, the acquired data is saved into a file and automatically

converted into an epoch file of 10 sec each, with 3 sec of data prior to the probe, and 7

sec data from the onset of the probe. The beginning and end of each probe are marked

in the epoch.

Signal Processing and Data Analysis

Before starting the auto-analysis, visual analysis of the entire EEG record of each

subject revealed adequacy of recording in all channels and absence of continuous

artifacts and fluctuations, which may render the recording not suitable for analysis.

Occasional movement artifacts would have been already detected and reported on the

screen against each probe in each epoch. To start the auto-analysis, the user must

enter the scenario numbers of the neutral probes. The analyses consist of systematic

and complex procedures involving computation of power-coherence measures and

detection of positive and negative responses in the frequency-time data of each probe.

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The moving window analysis program first compute the baseline parameters and then

determines the changes in the response segments and extracts predefined patterns if

they are present. The program automatically carries out the entire sequence of signal

processing, detection of predefines responses, their statistical analyses, interpretations,

and report generation. Based on the significant findings from the statistical analyses, the

program interprets the pattern of response detected with each probe and generates a

comprehensive report. The user has no role in the entire analysis except initiating it. It is

important to reject the data before analysis if it is visually unsuitable for the same.

A pattern of electrical oscillations accompanied by time domain changes

identified by the program during the presentation or immediately after the presentation

of a probe indicates presence of Experiential Knowledge. The authors have willfully

suppressed the technical details of the analyses as required and directed by the

pending patent application for this technology. A result screen displays the summary of

all the analyses. The results of all the statistical analyses are available for the user in

text format in different files. The program also produces several thousands of brain

maps and histograms of power spectrum and amplitude values for visual inspection and

comparisons. The program makes interpretations as per the inbuilt algorithm for

significant specific changes detected. When the pattern required for the identification of

Experiential Knowledge (EK) response is absent, the program interprets the identified

pattern as one of the cognitive processing stages viz. (1) Inattention (2) Primary

Processing, (3) Encoding, (4) Emotional Response, (5) Activity Suppression, and (6)

Familiarity. Primary processing and encoding are sequential cognitive processes

required for understanding the meaning of the probe, which may lead to retrieval of

experiential knowledge. Inattention represents absence of changes related to the

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presence of sensory processing in the EEG or absence of primary processing and

subsequent further processing. Similarly encoding represents absence of changes

beyond the process of predefined changes indicating semantic interpretation. Activity

suppression is defined to denote significant decrease in the power in different

frequencies in the sequence of data segments. Emotional response is defined to

represent similar changes as in activation suppression though significant changes

representing primary processing and encoding is present. Familiarity denotes presence

of topographically significant negative-positive components seen during or after the

presentation of a probe. However, none of these can be directly compared to the

presence or absence of regular ERP components obtained after data averaging and

recorded with stimuli of equal duration. Further developmental research for their

validation is in progress, and these results are not directly relevant for the purpose of the

present study related to sensitivity and specificity measures and hence attempt is not

made for a discussion of these results. The program comes out of the analysis loop if

conditions for the presence of any of these stages are absent, in which case it reports

the last satisfactorily resolved processing stage. “Experiential Knowledge” (EK) is

reported if all the assigned stages are satisfactorily identified by the program. After the

automatic analysis, the program prints out a report giving details of the scenarios,

probes, their codes, and the results of individual analysis of the probe, as well as list of

all preset conditions used for analyses. Additional report can be printed out which

arranges the probes in terms of relative strength of the activity related to EK, which

gives a comprehensive profile of the individual’s experiences related to the actions and

events referred by each probe. However, scores on these measures are not used for the

current analysis.

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Table 1Table 1Table 1Table 1

Mean and SD scores of sample variables in Experimental and Control Groups.

Variable Experimental Group Control Group Sig

Mean SD Mean SD

Age (in yrs) 36.8 16.0 36.9 14.8 NS

Sex Male = 30

Female = 26

Male = 28

Female =26 NS

Education (in yrs) 13.94 2.49 14.81 2.39 NS

Verbal Memory Trial 1 8.2 3.5 9.5 3.9 NS

Verbal Memory Trial 2 12.1 3.5 12.9 3.6 NS

Verbal Memory Trial 3 13.8 3.6 15.4 3.0 NS

Verbal Memory Delayed 13.7 3.0 14.4 3.3 NS

Visual Memory Trial 1 7.7 3.3 7.4 3.3 NS

Visual Memory Trial 2 11.9 4.0 11.5 4.4 NS

Visual Memory Trial 3 16.0 4.6 15.0 4.9 NS

Visual Memory Delayed 15.8 4.7 14.9 5.1 NS

SPM Percentile Score 73.8 12.9 74.4 13.1 NS

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ResultsResultsResultsResults

The score considered for the comparison of the two groups is the number of EK

responses produced by each subject in the BEOS profiling. The results of statistical

analysis of the scores on age, education and the results of the psychological tests in the

two groups are presented in Table 1. These results show that the two groups were

comparable on these measures and any significant difference seen in the mean EK

scores of the two groups cannot be attributed to differences in the basic sample

characteristics considered here. After an initial scenario wise comparison of the EK

scores in the two groups, Receiver Operating Characteristics Curve is computed using

the total EK scores in the two groups.

After the analysis of the EEG by the BEOS profiling program, the number of

probes eliciting Experiential Knowledge was counted in each scenario for each subject

in the two groups. Three sets of EK scores were derived for each subject, viz., 1) total

EK scores for scenarios 3 to 8 related to the activity in the ‘activity room’, 2) total EK

scores in sequence in scenarios 3 to 8, and 3) total EK scores for the scenario 9. A

sequence is defined to be present when a scenario has two or more probes showing EK

responses. Table 2 shows the mean and SD of the total EK scores for Scenarios 3-8,

total, and total within sequences, as well as the results of One Way ANOVA between the

two groups.

Page 22 of 45

Table 2 Table 2 Table 2 Table 2

Mean and SD scores of EK responses in Scenarios and F values in one-way ANOVA

between the EXP and CTL groups.

EXP Group CTL Group

F Sig§ Mean S.D. Mean S.D.

EK in Scenario 3 1.77 1.22 0.50 0.69 44.40 0.0000

EK in Scenario 4 0.68 0.81 0.17 0.38 17.80 0.0001

EK in Scenario 5 2.00 1.25 0.50 0.69 59.91 0.0000

EK in Scenario 6 1.70 1.25 0.41 0.53 48.90 0.0000

EK in Scenario 7 1.27 1.00 0.39 0.53 32.86 0.0000

EK in Scenario 8 1.98 1.34 0.59 0.79 43.42 0.0000

EK in Scenario 9 1.84 1.39 0.43 0.63 46.79 0.0000

EK in Scenarios 3-8 9.29 2.87 2.56 1.81 214.57 0.0000

EK in Sequence in Scenarios 3 - 8

7.64 3.64 0.78 1.21 173.57 0.0000

§ Significance level was adjusted after Bonferroni correction for multiple comparisons.

Significant differences exist between the mean scores of the experimental and

control groups in various scenarios and their combinations as shown in the Table 2. The

experimental group has significantly higher EK scores independently in all the

scenarios, totally, and totally within the sequence as defined earlier. Scenarios 2 to 8

have probes related to the activities carried out only by the subjects in the experimental

group. Scenario 9 presented at the end of 68 ‘activity’ related probes, elicited

significantly greater number of EK responses in the experimental group compared to the

control group despite the fact that at least 7 probes in the scenario 9 referred to some of

the activities that were common to the subjects in both the groups. The difference in the

Page 23 of 45

mean scores between the two groups in each scenario is remarkably significant in all

comparisons.

Receiver Operating Characteristic (ROC) Curve analysis was carried out using

the SPSS version 10, on the EK scores of the two groups for computing the sensitivity

and specificity related values of the test for identifying and differentiating the subjects in

the two groups. Figures 1 and 2 show the ROC Curves computed with total EK scores

and EK scores within each scenario, and total EK scores in sequences. The table

provides the sensitivity and specificity values of the test for the different cut off scores of

EK. With a cut off score of EK at ≥ 5.5 the test could discriminate the two groups with a

sensitivity at 0.91 and specificity at 0.94 (Table 3). The False Positivity and Negativity

scores were 0.07 and 0.91 respectively. The test has Positive and Negative Predictive

Values of 0.93 and 0.93 respectively at this level of sensitivity/specificity. Mean values of

total EK scores less than this cut off value reduce the sensitivity and specificity values of

the test. Mean values greater than 5.5 increases the specificity but markedly reduces

the sensitivity of the test, as could be seen in the Table 3. The mean value of the total

number of EKs in sequences within the scenarios 3 to 8 is a superior measure that

discriminated the two groups (Table 4). With a smaller (≥ 2.5) mean cutoff score of total

EK scores in sequences within the scenarios, the test has a higher sensitivity and

specificity of 0.95 and 0.94 respectively. Using sequence scores, the False Positivity

and Negativity scores were 0.04 and 0.07 respectively and the test has Positive and

Negative Predictive Values 0.96 and 0.93 respectively. Higher total EK scores (at ≥ 10)

in sequence increased the specificity to 1.00 though the sensitivity fell to 0.82.

Interestingly the Experimental group had significantly more number of EKs in the ninth

scenario compared to the control group though this was not in the expected direction. In

Page 24 of 45

Scenario 9, the experimental group had a mean EK score of 1.8 (SD = 1.4) and the

control group had a mean EK score of 0.43 (SD = 0.62).

Fig. 1.Fig. 1.Fig. 1.Fig. 1. ROC Curves of total EK scores within Sequence and for Scenarios 3 – 8

separately between the Experimental and Control groups.

Page 25 of 45

Fig. 2. Fig. 2. Fig. 2. Fig. 2. ROC Curves of total EK scores in Scenarios 3-8 within Sequences between the

Experimental and Control groups.

Page 26 of 45

Table 3 Table 3 Table 3 Table 3

ROC Curve values using total EK scores for Scenarios 3-8 area under the curve.

Area Under the CurveArea Under the CurveArea Under the CurveArea Under the Curve

Test Result Variable(s): EK 3-8

AreaAreaAreaArea Std. ErrorStd. ErrorStd. ErrorStd. Erroraaaa Asymptotic Asymptotic Asymptotic Asymptotic

SignificanceSignificanceSignificanceSignificancebbbb

Asymptotic 95% ConfidenceAsymptotic 95% ConfidenceAsymptotic 95% ConfidenceAsymptotic 95% Confidence

IntervalIntervalIntervalInterval

Lower BoundLower BoundLower BoundLower Bound Upper BoundUpper BoundUpper BoundUpper Bound

.989 .007 .000 .976 1.002

The test result variable(s): EK 3-8 has at least one tie between the positive

actual state group and the negative actual state group.

aUnder the nonparametric assumption

bNull hypothesis: true area = 0.5

Coordinates of the CurveCoordinates of the CurveCoordinates of the CurveCoordinates of the Curve

Test Result Variable(s): EK 3-8

EK score in Exp Group if Equal to or EK score in Exp Group if Equal to or EK score in Exp Group if Equal to or EK score in Exp Group if Equal to or

Greater thanGreater thanGreater thanGreater thanaaaa SensitivitySensitivitySensitivitySensitivity SpecificitySpecificitySpecificitySpecificity

-1.00a 1.000 0.000

.50 1.000 0.185

1.50 1.000 0.315

2.50 1.000 0.463

3.50 1.000 0.685

4.50 1.000 0.889

5.50 .911 0.944

6.50 .768 1.000

7.50 .750 1.000

8.50 .607 1.000

9.50 .429 1.000

Page 27 of 45

Table 4Table 4Table 4Table 4

ROC Curve values using total EK scores in Sequence in Scenarios 3-8.

Area Under the CurveArea Under the CurveArea Under the CurveArea Under the Curve

Test Result Variable(s): EK in Sequence in Scenarios 3-8

AreaAreaAreaArea Std. ErrorStd. ErrorStd. ErrorStd. Erroraaaa AsymptoticAsymptoticAsymptoticAsymptotic

SignificanceSignificanceSignificanceSignificancebbbb

Asymptotic 95% Confidence Asymptotic 95% Confidence Asymptotic 95% Confidence Asymptotic 95% Confidence

IntervalIntervalIntervalInterval

Lower BoundLower BoundLower BoundLower Bound Upper BoundUpper BoundUpper BoundUpper Bound

.977 .014 .000 .949 1.004

The test result variable(s): EK in Sequence has at least one tie between the positive

actual state group and the negative actual state group.

aUnder the nonparametric assumption

bNull hypothesis: true area = 0.5

Coordinates of the CurveCoordinates of the CurveCoordinates of the CurveCoordinates of the Curve

Test Result Variable(s): EK in Sequence in Scenarios 3-8

EK score in Exp Group if Equal to or Greater EK score in Exp Group if Equal to or Greater EK score in Exp Group if Equal to or Greater EK score in Exp Group if Equal to or Greater

ThanThanThanThanaaaa SensitivitySensitivitySensitivitySensitivity SpecificitySpecificitySpecificitySpecificity

-1.00a 1.000 0.000

1.00 .982 .667

2.50 .946 .944

3.50 .875 .963

4.50 .821 1.000

5.50 .696 1.000

6.50 .589 1.000

---- ----- -----

15.00 .036 1.000

16.50 .018 1.000

Page 28 of 45

Figure 3 shows percentage of subjects showing different EK scores. Thirty-four

percentages of the experimental subjects has shown maximum EK scores in the range

of 9 – 10. The distribution of experimental subjects with different EK scores appears to

have a normal distribution. Correlations of EK scores with different sample

characteristics, shown in Table 4 do not also reveal any significant values to indicate

that presence of EK been influenced by any sample characteristic. No significant

correlation scores are obtained between total EK scores and psychological test scores

except in the third trial immediate verbal recall scores, at the 0.05 level of significance.

Fig. 3. Fig. 3. Fig. 3. Fig. 3. Percentage of subjects with different range of total EK scores in the experimental

(EXP, N = 56) and control (CTL, N = 54) groups.

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Table 5Table 5Table 5Table 5

Correlation coefficients (Pearson r) between total Experiential Knowledge Scores, and

Sample characteristics and psychological test scores in the Exp group.

Subject and other Test Variables CorrelationCorrelationCorrelationCorrelation

Age - 0.05

Education -1.40

Income 0.02

General Health Questionnaire Scores - 0.10

Verbal Learning-Memory Test - Immediate recall Trial 1 - 0.10

Verbal Learning-Memory Test - Immediate recall Trial 2 - 0.10

Verbal Learning-Memory Test - Immediate recall Trial 3 - 0.22****

Verbal Learning-Memory Test - Delayed recall - 0.10

Visual Learning-Memory Test – Immediate recall Trial 1 0.05

Visual Learning-Memory Test – Immediate recall Trial 2 0.005

Visual Learning-Memory Test – Immediate recall Trial 3 0.11

Visual Learning-Memory Test – Delayed recall Trial 0.06

Raven's Standard Progressive Matrices Score 0.02

* Significant at 0.05 level

A very low but significant negative correlation (at 0.05 level), is seen between the verbal

memory trial 3 scores and EK scores in the experimental group.

Discussion

Discussion of the results is based on the interpreted results of the BEOS profiling

generated by the NSS. The most important result is the presence of ‘Experiential

Knowledge’, reported by the NSS based on the analysis of the changes in the EEG

activity time locked to the probe and in comparison with the pattern detected in the

preprobe segments in each electrode channel and in each trial related to a probe. The

distributions of EK scores in the two samples are markedly diverse as seen in the Figure

3. The results of the BEOS profiling show that EK responses were indeed present in the

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experimental as well as control groups, though there is significant difference between

the mean scores of the two groups. A striking finding is that of the 68 probes used in the

scenarios 3 to 8, only mean 9.3 (SD=2.9, 13.68%) probes elicited EK responses in the

experimental group. Comparatively, the presence of EK response in the control group is

insignificant indeed (mean 2.6, SD=1.87, 3.82%) contributing to a very significant

difference between the two mean scores. It does not warrant that each probe shall elicit

a specific remembrance. Subjective reports of individual on the content of remembrance

show that once a probe triggers remembrance, chunks of related information may flow

in. Additional probes presented during this period do not show significant difference in

the probe related changes in comparison with the preprobe baseline. The present

analysis does not attempt to determine the total duration of such changes once a probe

initiates the changes. Additional cueing can enrich remembrance only if one has missed

important pieces of information during the recall and the preprobe baseline activity has

subsided.

That only one out of fourteen probes elicited EK response may also suggest

different possibilities for the outcome. One is that the preset conditions used in the

signal detection and analysis of EK responses are very stringent affecting the sensitivity

of measurement of EK responses. The three probe that elicited maximum EK responses

are “There was a bottle of water on the table” (29%) and “I closed the wooden box”

(25%), and “I collected the broken pieces of the piggy-bank” (23%). Another possibility is

that the experimental subjects participated in a set of routine activities, which did not

have any significant personal value to them influencing the recall processes and the EK

responses. A third explanation may be found in the possibility that many of the

remembrances of experiences may be in the form of recall of transcoded information

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assembled at a later stage, rather than the remembrance of the original activity, as in

the case of recall of many other logically assembled units of information. There may be

obviously no need to access source memory details and recreate the components of the

original experience, every time one recalls the details of the event, as they do not have

any emotional value to the individual. Even experientially acquired information may get

transcoded, interlinked with other existing pieces of conceptual information already

present in memory, and thereby becomes consolidated (86-93). These studies indicate

that accessing the hippocampus is an important requirement for the retrieval of

autobiographical episodes. However, once consolidated, one can directly recall

semantic and episodic information without accessing the source memory, for which

accessing the hippocampus may be necessary (94).

The control group showed a few EK responses in scenarios 3 – 8 despite the fact

the subjects in the group did not carry out the task. The fact that the control groups had

not only known about the activities, but they had also seen the associated objects in the

‘activity room’ just before the BEOS profiling were not good enough for producing the

neural changes responsible for the EK responses. Despite this, the results of the One

Way ANOVA given in the Table 2 clearly support the ability of the test to differentiate the

two groups using the response of “experiential knowledge” of actions carried out by

subjects in the experimental group. The total EK scores, EK scores in sequence, and EK

scores in each scenario can significantly differentiate the experimental group from the

control group.

ROC Curve analysis of the three sets of EK scores supports the strength of the

procedure for identifying persons with specific experiences, provided there is no reason

to believe that the probes could have elicited any other associated remembrance. The

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association between a probe and the content of remembrance if provoked by it is

presently inferential as we presume that a specific probe must have provoked an

associated remembrance. There is no clue to the possibility if a probe has provoked a

remembrance different from one what one was expecting. However, the strength for

such inference arises from the fact that sequence of probes has triggered EK responses

in different scenarios in the experimental subject. Further, there is no reason to consider

that the subjects in the study could have indulged in an unrelated mental processing that

produced EK responses while listening to the probes.

Sensitivity and specificity scores obtained from the ROC analysis using scenario

wise EK scores have much lesser capability for discrimination of the two groups. ROC

Curves of the total EK scores and the EK scores in sequence shows excellent

probability (higher than 90%) for the procedure to differentiate the two groups and

identify an individual who took part in an activity referred in the probes. An important

aspect of the test is that EK response on single probe alone is not good enough for the

classification or identification of a subject. Multiples of probes showing EK responses in

sequence are required for deciding on the participation of an individual in an activity with

adequately high specificity. It is characteristic feature of the test that it allows testing

such multiple points of references. Greater the number of probes with EK, more certain

one can be about the diagnostic interpretation derived from it. Greater the number of EK

scores, especially of probes linked with one another, the confidence level of diagnosis

may become close to unity as seen in Table 4. EK scores equal to greater than 4.5 in

sequence yields a specificity of 1.0 though sensitivity falls to 0.82 and lower. Deciding

on participation in an activity using a few EK scores increases the possibility of false

positivity and false negativity increases and hence it is prudent to avoid such

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interpretation based on low EK scores. There does not appear to be a case emerging

from the present results to pre-decide what must be a cut off score. Sensitivity is very

high with low scores and it falls as specificity rises. Keeping the computational

parameters of BEOS profiling constant, the cut off score and the total EK scores may be

considered a function of the complexity of the experiential nature of the episode and the

presence and accuracy of the probes referring to them. This is bound to change from

event to event and from individual to individual. It is apparent that the cut off scores seen

to differentiate the two groups in this study cannot be used if another task or experiential

situation is used with different number of probes. This is a strong point for consideration

during interpretation of the results if an individual is tested without an appropriate control

condition. The control probes that are to be used in such situation are expected to

overcome this difficulty in the sense of the appropriateness of its usage, as they can

help in the self-validation of the results. A self-validation using control probes may be

considered a superior alternative to using another person as control and using

contextually irrelevant probes on that subject. However, it would also depend on the

vividness of the experiences to be used for control probes, which in turn may depend on

independent confirmation of the experiences used for designing them. A significant

aspect that emerged in the study is that the probes producing EK scores support recall

of sequence of the related activities, a finding significantly absent in the control subjects.

The results indicate that the presence of EK responses on interrelated probes in

sequence is a sure way of identifying participation of a subject in an activity investigated.

Temporal sequencing has been reported an important factor in all encoding. True

sequencing is the basis of logical connectivity of events. Sequences encoded in

experiences are as understood or interpreted by the participating or witnessing

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individual, which may differ from the true sequences of events. However, these

sequences are important links for retrieving information logically. The brain does not

have a temporal clock by which it could use to go to a specific point in time and retrieve

whatever information stored at that point in time. Time estimation is made as before and

after a particular episode that can be remembered. Therefore, remembering the episode

and the sequence of events are important requirements for arriving at a period.

Searching the past appears to be a function of the retrieval of content of an event in

reference to a personal context or event, which serve as the personal clock. Personal

significance is the most important factor that facilitates recall of experiences, whereas

logical associations (95) may be the factor that need to be used for the recall of

impersonal information. The mechanism of storage appears to consider the events as

they are perceived to have happened as well as known to have been executed by the

self. Links across events occurred at different points in time may be encoded at any time

during their remembrance. Therefore, remembrance of personal significance is an

important requirement for the brain to retrieve the core episode and whatever happened

prior to or after it. The sequences interpreted or detected serve the rule for storing the

order of events in a time locked brain. Studies have shown the presence of temporal

gradient in the brain involving the entorhinal cortex (96) and other several cortical areas

(97,98) centered on the perception of familiarity of famous faces over long time intervals

in life. Maguire & Frith (99) found evidence for the role of the bilateral hippocampus for

the recall of autobiographical episodes, in which they inferred that the left hippocampus

might be related to all such personal recalls whereas the right may have a temporal

gradient based on the remoteness of the memory recalled. In BEOS profiling, great care

must be taken to maintain the sequence of components of events that are investigated,

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whether they are verified or hypothetical. This seems to have an effect on the presence

of EK scores to sequentially presented probes. The study does not consider the effects

of random presentation of probes. The examiner arranges the probes strictly in a

sequential manner, best known or considered possible by the examiner.

The task used in the ‘activity room’ comprised of normal activities in life except

breaking the clay piggy bank with an iron rod and collecting the coins from it. The most

significant aspect of the study reported by the subjects was the strangeness

experienced by the subjects that the said tasks were carried out in the laboratory of a

scientific institution. This is the central theme, which made the test memorable for many

as revealed in the post-test interview of some of the experimental subjects. It may be

presumed that the different insignificant components of the activities were linked to this

core theme and the subjects could retrieve them too. That the subjects were informed

the purpose of the study in the beginning itself could also have contributed to their

intention to remember the activities they carried out so that they could recall them during

the BEOS profiling. Such intention was obviously not present in the control subjects as

they did not to carry out the activities. The post-test interview further revealed that the

subjects in the experimental group indulged in anticipating the probes as they referred to

the sequence of actions they had carried out during the test, which was totally absent in

the control group despite the fact they had known the probes beforehand.. The post-test

interview of the control subjects revealed mere knowledge of the contents of some of the

probes they heard. They also remembered and reported their first visit to the laboratory.

There is no error in assuming that there could have been changes more subtle and short

lived than measured by the program. A serious difficulty with the measurement

procedure is the absence of an objective criterion for calibration of the neurocognitive

Page 36 of 45

process of remembrance, which can affect the sensitivity of the measurement system.

The preset conditions used in the signal detection and analysis of EK responses may

have been very stringent affecting the sensitivity of measurement of EK responses,

because of which only less than one third of the probes elicited EK responses.

The two sample groups used in the study have not shown any significant

differences with regard to psychological test scores. The two groups had subjects in a

wide age range of 15 years to 70 years, with comparable mean ages. The two groups

were also comparable in their mean number of years of education. With regard to

memory, the immediate recall and the delayed recall scores were comparable in the two

groups. The findings indicate that age related or any of the psychological factors of the

sample tested have not contributed to the differences in the EK scores of the two

groups. Significant personal experiences may alter or influence earlier related

experiences and their interpretations. However, the present study does not enquire this

aspect.

An important aspect of the study is that the subjects who carried out the activities

as per the instructions given could sit through the BEOS profiling, with a frame of mind,

which did not necessitate them to offer any resistance to a process of normal

remembrance of the activities they had carried out. There was no need for them to think

either that they had carried out an unacceptable act by breaking the piggy bank and

removing the coins, or they were to pretend that they had not done the same. The

probes were familiar to them, as they had heard them before and knew they were not to

respond to them. The post-test interview showed some degree of eagerness on their

part by anticipating the probes. Even the control subjects were primed with information,

which could facilitate retrieval of visual images presented a few minutes back, which

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could also cue remembrance of any other event in their personal life. There is no reason

to consider that the neural changes indicated by the EK response may be representing a

contextually different remembrance in the subjects. However, this is an issue, which

needs serious consideration, as the neural process measured only represents a

cognitive process and not the content. The temporal proximity the neural activation and

the associated cognitive process, and the contextual relevance of the cognitive task as

inferred from the test instructions make us the inference about its content. A neural

activation measured during a cognitive process only indicates the presence of the said

cognitive process and may not represent its content. The coding used with the probes

has directed the program to look for specific changes that indicate the presence and

type of mental imageries, but does not go beyond it to give information about the content

itself of the remembrance. This is an important issue for consideration if the test is to be

used for forensic purpose. There are also possibilities of intentional efforts by a subject

to alter the content of remembrance or the subject retrieving a contextually different

theme. For example, trauma experienced during an elaborate interrogation may become

associated with a probe, and the probe may help to remember the trauma producing an

EK response, though there may not be any other experience itself associated with it. It is

equally important that the mental state of the subject must be conducive for

remembrance of past events. This is unlikely to happen if the subject is emotionally

tense and disturbed, while listening to the probes.

The results of the study further indicate the need for systematic understanding of

the mechanisms and factors that influence the process and the quality of remembrance

of personal experiences, especially with reference to the procedure used in the study.

Absence of Experiential Knowledge in BEOS profile may not necessarily indicate that

Page 38 of 45

the individual did not have the experience, as the ability to remember an

autobiographical episode depends on its personal significance to the individual over

time. A few random EK scores on the BEOS profiling elicited by probes may also not be

enough to infer that the subject has had those experiences contextually specific to the

probes, as a probe may trigger recall of contextually unrelated episode, when the entire

scenario has no personal significance. However, the presence of Experiential

Knowledge to sequence of events referred by probes is indeed a strong indication of the

presence of occurrence or participation in the episode. Results strongly suggest that

awareness or presence of EK responses occurring in such sequence do not indicate

remembrance of unrelated personal episode. Remembrance in sequence represents the

logical connectivity of the components of the experience, which unrelated probes cannot

elicit in a random manner. On the other hand, absence of significant EK responses is

equally strong indication of the absence of experiential knowledge because the

individual has not participated in the said actions.

It is unlikely that one may fail to recall personally significant autobiographical

episodes unless there is interference in terms of a disease process or any other

traumatic condition in the individual. The duration between the original experience and

the time of its remembrance and presence of emotional states in which one intends to

remember or encounters a cue may also have important influences on the vividness,

quality, and content of remembrance. Intense emotional experiences may render the

vividness and quality of remembrance of earlier personally significant experiences.

Personal episodes frequently remembered do have chance of easy recall as they would

have already been transcoded and linked to several other units of information in the

knowledge bank. Retrospective transcoding of experiences based on new experiences

Page 39 of 45

and interpretation may influence their subsequent remembrances. It is presently a mere

guess if subjects who took part in the above activities will remember them as an

experience or an idea, a few months or years later. The volunteers took part and carried

out the activities willingly, though the activities did not have any personal significance to

the participant, except the possible excitement and the reward. Irrespective of this, the

test could show presence of experiential knowledge in those subjects who had

participated in them. There is indeed significant differences between the profiling of the

experiences of a subject in a laboratory based experimental study and testing a subject

for the presence of experiential knowledge acquired in real life situations. In the second

case, the formulation may always have hypothetical possibilities. Several ecological

factors, which escape quantification, may influence the results. It is indeed very

important to establish the ecological validity of the test before using it as a diagnostic

tool. This is all the more important when the test is to be used as a forensic tool for

investigation of suspects and accused persons.

Page 40 of 45

Acknowledgements

This research paper is based on the data collected in a project entitled “Normative Data

for Brain Electrical Activation Profiling” conducted by the Directorate of Forensic

Sciences, Gandhinagar, India. The authors are thankful to Technology Information

Forecasting and Assessment Council (TIFAC) of the Department of Science &

Technology, Govt. of India, New Delhi for awarding the grant to conduct this study. We

are also thankful to the Directorate of Forensic Sciences, Ministry of Home Affairs, Govt.

of India, New Delhi, and to Directorate of Forensic Sciences, Gandhinagar, specifically

to the Director and Additional Director of DFS, Gandhinagar for their valuable support

for conducting the study.

The authors also thankfully acknowledge the valuable suggestions and comments

offered by Prof. C.R. Mukundan's former students and neuroscientists in the United

States: Madhavi Rangaswamy, PhD, Chella Kamarajan, PhD, Roopesh B. Nagaraj,

PhD, and Ashwini Pandey, PhD at SUNY Downstate Medical Center, NY, as well as

Ajayan Padmanabhapillai, PhD at Kirby Forensic Psychiatric Center, NY.

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